Soft material loading apparatuses have a wide variety of applications including research and development of tissue samples. For example, such apparatuses enable one to study the changes in the biochemistry and physiology of cultured cells under conditions of mechanical strain as compared to cells grown conventionally under quiescent conditions. In addition, such apparatuses allow one to culture cells in 3D matrices or tissue explants in simulated physiological conditions, thereby providing cells and/or tissues that are suitable for surgical implants.
Without being bound by any theory, it is believed that mechanical stimulation of cells is believed to influence the biochemistry and physiology of cells. Such a stimulation provides enhanced production and, therefore, improved harvesting efficiency of biochemical products from these cells. Various systems have been proposed previously for growing cells in culture and/or tissues. A few systems have attempted to account for the natural mechanical environment of cells or tissues. One typical conventional system attempts to uniaxially elongate smooth muscle cells in culture (see, for example, Leung, D., et al, Science, 1976, 191, 475-477), but fails in part because uniaxial stretch is not physiologic and the strain distribution in this system is not uniform and, therefore, not well-characterized for the population of cells stimulated.
In another conventional system, cells in culture are subjected to a uniform shear strain, constant in magnitude and direction. See, for example, Davies, P. et al, J. Clin. Invest. 1984, 73, 1121-1129. This system is not generally applicable because inter alia (1) endothelial cells are the only cells subjected to shear strain in vivo thereby limiting its applicability to only this one cell type and (2) shear strain in vivo occurs simultaneously with biaxial tension, and, by uncoupling the two, the true mechanical environment of endothelial cells is not reproduced.
Regardless of the application, conventional soft matter loading instruments typically use direct drive electromagnetic armatures. The advantages of direct drive include speed and controllability while utilizing minimal moving parts. However, the deliverable force tends to be small because the conversion of electrical energy into useable mechanical work is extremely poor. Most of the energy winds up as heat dissipated in the electromagnet.
Accordingly, there is a need for soft material loading apparatuses that do not utilize conventional direct drive electromagnetic armatures. There is also a need for soft material loading apparatuses that can provide artificial conditions sufficient to allow production of tissue samples that are suitable for surgical implants.